The central nervous system, made primarily of the brain and the spine, is a vital part of the human physiology responsible for coordinating many aspects of human activity. The spinal cord is made up of a bundle of nerve tissue and acts as a conduit to communicate neuronal signals from the brain to the rest of the body. Protecting the spinal cord is the spinal, or vertebral, column. Anatomically, the spinal column is made up of several regions, including the cervical, thoracic, lumbar and sacral regions, each containing a plurality of vertebrae.
While most people have fully functional spinal cords, it is not uncommon for individuals to suffer some type of spinal ailment. For example, spinal fractures, or vertebra compression fractures, occur when one of the bones of the spinal column fractures. Such an event is often accompanied by sudden onset of pain in the back which intensifies when sitting or standing and decreases when lying down. The pain associated with vertebra compression fractures can be strong enough to limit the activities a person can undertake, thereby reducing the overall quality of life of the individual.
Spinal fusion is a surgical technique used to join two or more vertebrae. Such procedure is common for individuals suffering from a variety of spine related diseases, such as vertebral fracture. The fusion process typically involves stabilization of the vertebra using metallic screws, such as pedicle screws, rods, plates, or cages. Minimally invasive percutaneous techniques currently practiced utilize pedicle screw systems having a cannulated screw in order to use a guide wire for proper placement. U.S. Pat. No. 7,780,706 is an illustrative example of a pedicle screw assembly having a cannulated pedicle screw. In these procedures, the cannulated screw is passed over a guide wire which was positioned prior to the placement of the screw over the guide wire. While such technique is relatively safe and effective, several possible problems are known to exist.
Use of a guide wire in pedicle screw placement poses several possible risks to the patient. First, guide wires may advance through softer cancellous bone. If such event occurs, severe damage may result to the organs or vessels. Second, when placing guide wires in position, they need to travel a great distance. Such increased distance sometimes results in the guide wires forming kinks, becoming bound within the screw. Fixing the problem can be difficult for the surgeon, increasing the risk of the guide wire being advanced into a critical vessel. Use of guide wires cause increased length of surgical instruments. The increased length makes the instruments more cumbersome, particularly when moving around fluoroscopic imaging devices, such as C-arm, which are critical for percutaneous screw instrumentation. When using guide wires, cannulated screws are required. Since these screws have hollow sections therein, they are inherently less strong than solid screws. Finally, procedures which use guide wires require additional instrumentation, such as retraction devices.
Accordingly, what is needed in the art is a pedicle screw system, device, method, and kit that does not require the use of a guide wire for proper implantation.